Resealable closure devices of the "inverted umbrella" type for use on a metallic cans are known. U.S. Pat. Nos. 4,574,975 and 4,632,271 each describe a resealable closure device similar to that used in the present invention. The disclosures of U.S. Pat. Nos. 4,574,975 and 4,632,271 are incorporated by reference and relied upon in this disclosure.
The known closure devices comprise two components: a metallic end and a flexible closure element. The metallic end may be sealed to a can body using conventional sealing techniques, such as double sealing, or by such means as adhesive bonding. The metallic end has an opening which is surrounded by an outwardly directed and upstanding beaded, hemmed or curled flange. The flexible closure element forms a resealable closing device. This closure element includes a central panel which closes the opening in the metallic end and a lever and nose which are activated to seal the closure element onto the end. The nose does not hook under the edge of the hemmed flange, but is tightly held against the flange by tension within the closure element, as well as by the internal pressure within the canned body, when so filled.
Methods of detecting tampering with the contents of the container are also known in the field of resealable containers. For example, U.S. Pat. No. 4,580,692 discloses a general openable panel which must be broken open by pressure exerted on the openable panel before the liquid may be dispensed from the container. A scored edge around the openable panel permits the consumer to identify whether the container has been opened prior to purchase by observing whether the scored edge is broken or intact.
FIGS. 6-8 of U.S. Pat. No. 4,580,692 show that the closure element may be used to mash against the openable panel to break a scored edge around the periphery of the openable panel. In this embodiment, the consumer would mash n the closure element until an annular extension on the closure element breaks the openable panel from the metallic end about the peripherally scored edge.
Thus, openable panels and closure elements adapted to open the openable panels, in general, are known. However, prior art opening devices are incompatible with the more advantageous umbrella type closure structures. Thus, an openable panel and an opening closure element are needed which are adapted to the particularly advantageous structure of the umbrella type closure device shown in, for example, the U.S. Pat. No. 4,632,271.